Israel Air Force planes struck a bridge in the southern suburb of Beirut, a Hizbollah stronghold, and the fuel stores of the Jiyyeh power plant south of the city early on Friday, witnesses and security sources said.

The Lebanese Army responded with anti-aircraft fire. Residents heard at least three strikes but there was no immediate word on casualties.

The impact of at least four missiles were heard. Anti-aircraft fire from the ground echoed in other suburbs of Beirut as the planes roared over the Lebanese capital.

There was no immediate word on casualties.

Israeli officials have said that south Beirut, a densely populated neighborhood of Shiite Muslims where Hezbollah has its political headquarters, could be targeted. Leaflets dropped in the evening warned people to stay away from Hezbollah offices.

Hezbollah leader Sheik Hassan Nasrallah has his office and residence in the district of Haret Hreik in south Beirut. Hezbollah's Shura Council, its decision-making body, and the TV station are also located in that area, a section heavily guarded by Hezbollah.

Israel has intensified its attacks on Lebanon, striking bridges, roads, and the runways of the international airport and two major army air bases to put pressure on the government and force Hezbollah to free two Israeli soldiers the guerrillas captured Wednesday.

IAF aircraft struck the main highway linking Beirut to the Syrian capital Damascus early on Friday, a Lebanese security source said.

The jets struck at least five separate times along different points of the international route, the source said.

It was not immediately clear if there were any casualties and witnesses said the road was clear of traffic after earlier congestion as tourists fled Lebanon to neighbouring Syria.

IAF planes struck the main highway to Beirut's international airport and the south of the country early on Friday, security sources said.

The Lebanese Army responded with anti-aircraft rounds. The airport had already been closed due to an Israeli aerial assault on its runways on Thursday.